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Ostracoda (Crustacea) biodiversity: a taxonomic and functional approach.The impacts of human actions, as deforeations, pollution and introduction of species have been causing negative effects on the environment. The extinction of species, and change of distribution range, are some of them, especially in the aquatic environment were it is observed a hogh richness compared to its extension. Thus, the knowledge about biodiversity is of extreme importance conservation of ecosystems. Ostracods are one example of a group constantly affected but ill studied. It was performed a revision of Cyprettinae s.l. from circumtropical regions, using morphological taxonomy. The first step in the revision of Cyprettinae s.l. was redescribe the type species of Cypretta Vavra, 1895 from the original type material, discuss the morphology and diagnosis of the genus. After that it was described two new species from Pseudocypretta Klie, 1932 genus from South Africa and Brazil; and described a new genus and four new species from Brazil. With the redescription of the type species of the Cyprettathe diagnosis characters for the species and genus were delimited. Analyzing the features of the new species of Pseudocypretta this genus was moved from the Cyprettinae subfamily to the Cypridopsinae subfamily, and expanded the distribution of this genus to the Afrotropical and Neotropical regions. The new genus and new species were recorded from the four main floodplain of Brazil and were designated to the Cyprettinae subfamily. Both Cypretta, Pseudoypretta and new genus are characterized by presence of septas in its valves, however they vary in level of development (complete or incomplete) and disposition along the margins of the valves. Using a database of ostracods distribution and ecological niche modelling (ENMs) the effects of climate change were evaluated to the functional diversity of ostracods in the South Cone of South America, in the moderate-optimistic and pessimistic scenarios of 2050 and 2080. It is projected that the ostracod functional diversity will suffer a gradual reduction in 2050 and 2080on bothscenarios of carbon emission, but especially in the pessimistic scenario of 2080. The results highlight the importance of evaluate the functional diversity for ostracod conservation, since several areas marked to have low taxonomic richness supported intermediate and high levels of functional diversity.
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Diversidade beta espacial e temporal de peixes em um rio tropical fragmentado.The overexploitation of natural resources by human beings in recent centuries has had serious consequences for biodiversity. In freshwater aquatic environments, organisms suffer from various degradation processes, which involve pollution, environmental fragmentation, introduction of invasive species, among others. The construction of dams and reservoirs for energy production is among one of the biggest reasons for the degradation of these environments, as this fragments the water body, preventing connectivity between sites, in addition to transforming the lotic environment into a lentic one, completely changing the dynamics of the local. As an aggravating factor, there are reservoir cascades, which consist of a sequence of reservoirs built on the same river, enhancing the negative effects of a single reservoir. In highly fragmented environments, physical-chemical changes occur, which harm the local biological communities. Thus, in this work, analyzes of the spatial and temporal beta diversity of fish were carried out in a very fragmented river in northeastern Brazil, the São Francisco River. For spatial beta diversity, we calculated the Local Contribution to Beta Diversity (LCBD), taxonomic and functional, at 28 points along the six reservoirs and in a lotic stretch downstream of the reservoirs, up to the mouth. We performed a beta regression model to verify the relationship between LCBD values and environmental variables collected in the same period. As a result, we found that the points of the initial reservoirs and the points closest to the mouth of the river were the ones that most contributed to beta diversity, both taxonomic and functional, and turbidity was the variable that was most positively associated with LCBD values. For the temporal beta diversity analysis, we used five reservoirs, and compared the beta diversity between pairs of months over years. A correlation was also made between the results of temporal beta diversity and the variation of environmental variables. There was no relationship between environmental variables and temporal beta diversity. However, it was possible to observe that the reservoirs that operate as a trickle of water had the most unstable and unpredictable temporal beta diversity values, while the reservoir that operates as an accumulation followed the pattern of seasonal variation of the dry-flood dynamics. We recommend the proper management of the reservoirs of a waterfall, monitoring the variations in the parameters and regulating the flow and water level according to the expected natural variations, mainly the initial ones that function as sources of species and functional traits, and also the preservation of the rivers tax. We conclude that deeper studies covering other periods must be carried out, to complement the existing data and provide greater assertiveness in decision-making and conduction of reservoir operations.
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Redescrição de Platanichthys platana (Regan, 1917) (Clupeiformes, Clupeidae) com comentários sobre a distribuição geográficaA taxonomic and biogeographic review for the genus Platanichthys was necessary. In recent years, they have been identified as being of the species Platanichthys platana specimens collected in rivers and lakes of other hydrographic basins besides the then known ones. The species considered the smallest sardine in Brazil, always found in continental and coastal environments, including estuarine regions, began to be captured in waters of regions more in brazil, thus raising the hypothesis that these new specimens are a new species of the genus, until the monospecific moment. A total of 478 specimens identified as Platanichthys platana, from seven different hydrographic basins of South America (Baixo Paraíba do Sul, São João, Ribeira de Iguape, Alto Paraná, Guaíba, Atlântico Sul and La Plata), were analyzed. 40 morphometric analyses were performed, 21 non-overlapping (truss), and 13 additional morphological analyses. The differences observed between the analyzed populations didn’t support the hypothesis of being a new species for the genus Platanichthys, but after the analysis of all the material, it was possible to better determine its geographical distribution is to elaborate a better diagnosis for characterization and differentiation of the species in relation to other similar Clupeideos.
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Human-induced pressures driving biodiversity and functioning o freshwater ecosystems.Many studies have shown that human-induced pressures are causing species loss across many trophic groups, with potential negative effects ability of ecosystems to maintain functions and provide services to human well-being. However, evidence for this prediction is still lacking in freshwater ecosystems. In this document, we report the results of four studies that investigated the effects of human-induced disturbance on (i) biodiversity, (ii) ecosystem functioning, and (iii) biodiversity-ecosystem functioning relationships. These studies were conducted in different freshwater ecosystems and encompassed multiple spatial and temporal scales. In the first study, we used a 12-year data set from a shallow lake displaying shifts between three alternative states (clear, turbid and shaded). We investigated how the biodiversity (taxonomic and functional) of fish and zooplankton, ecosystem multifunctionality (provision of multiple ecosystems functions simultaneously) and their relationships were affected by shifts between alternative states. Biodiversity of fish and zooplankton and multifunctionality enhanced during clear-water state, but decreased during turbid and shaded states. The relationship between biodiversity and multifunctionality was strongly positive during the clear state, but weakened after the lake shifted to turbid and shaded states. In the second study, we used a dataset of 72 lakes from four large Brazil wetlands to examine how increased human pressure (human footprint) affected the relationship between the biodiversity (taxonomic and functional) of seven groups of aquatic organisms and multifunctionality. The biodiversity of most organismal groups was positively associated with multifunctionality. However, increased human pressure has weakened these relationships, and for some groups these relationships have become negative. In the third study, we used a dataset of 61 streams from two Neotropical biomes (Amazonian rainforest, Uruguayan grasslands) to investigated how increased cover human land-uses (agriculture, pasture, urbanization and afforestation) affected the biodiversity (taxonomic and functional) of fish, arthropods and macrophytes, and the consequences of this for animal biomass production. In both biomes, the biodiversity of animal and plant assemblages decreased with increasing cover of land-uses. Land-uses reduced animal biomass through direct and indirect pathways mediated by declines in biodiversity. In the fourth study, we investigate how increasing human pressure affects fish diversity and the consequences of this for energy flux in fish food webs over 17 years in a subtropical river (Uruguay River). Human pressure was associated with temporal declines in diversity and energy flux in all fish trophic compartments, and the relationship between diversity and energy flux weakened over time. Collectively, these studies reveal that human-induced disturbances reduce the biodiversity of various groups of organisms in different types of aquatic ecosystems. The decline in biodiversity, in turn, reduces the ability of these ecosystems to sustain multiple functions.
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Dormant structures of aquatic microfauna: ecological aspects and perspectives on different climate temperature scenarios.Dormancy is a biological process that allows communities to survive in adverse environmental conditions. The production of dormant structures is one of the main strategies performed by aquatic microfauna (ciliates, rotifers, cladocerans, copepods and ostracods). This study aimed to evaluate the dormant structures of aquatic microfauna, addressing different ecological aspects such as hatching time, dispersal, fungal influence and viability of the structures at different temperatures. The hatching experiments were performed with sediment and aquatic macrophytes of lakes from the upper Paraná River floodplain, Brazil. The results evidenced that ostracod resting eggs have similar hatching times among taxonomically close species and that the functional traits of the species (e.g. body size and presence of spines) influence the hatching time. In addition, dried roots of the free floating macrophyte (Eichhornia crassipes) shelter and disperse ostracod resting eggs. While, for all dormant aquatic microfauna a positive effect was observed between the presence of fungi in the sediment and species richness of the dormant communities, which did not negatively influence the viability of the dormant structures. The results also showed that the increase in temperature reduced significantly the species richness of the dormant microfauna and led to homogenisation of the egg bank. Based on the results, we highlight the importance of dormant structures in the recolonisation of environments and the high potential for dispersal by biotic vectors (plants), however this is also a warning for the invasion process. In addition, climate change responsible for temperature increase is a threat to the dormant structures of aquatic microfauna, thus it necessary to create mitigation measures for the conservation of the egg bank.
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Efeitos da invasão de espécies de Cichla nos padrões taxonômicos e funcionais da assembleia de peixes da planície de inundação do alto rio ParanáInvasive species cause loss of diversity in introduced sites. Species of the genus Cichla, popular tucunaré or peacock bass, are known for their voracious behavior that makes them a target in sport fishing and a predator with great negative impacts on introduced sites. There is a visible controversy around the species, since the scientific literature points out more and more impacts and the legislation seek ways to increase introductions, generating propagule pressure and prohibiting fishing in invaded places. In addition, mostpapers are punctual and in anthropized places such as reservoirs. Thus, we investigated how the abundance of Cichla individuals affects the assemblage of a floodplain over a time series. We investigated the effects of Cichla on taxonomic attributes of the assemblage (richness, evenness, diversity, abundance, and body length) and on species composition (beta diversity). In addition, the effects of Cichla on functional indices of the assemblage (functional richness, functional equitability, functional divergence, and functional dispersion) are investigated. Cichlaimpacts were evident in changes in beta and functional diversities. Cichla helped in the fauna homogenization process, increasing nestedness and reducing turnover. Additionally, it increased species with similar and more common traits and reduced species with rare traits, reducing dispersion, evenness, richness and functional divergence, it is worth noting that some results appeared with a delay, that is, some impacts make some time to appear in the invaded assembly.Our results showed that Cichlaspecies are capable of changing diversity patterns even in natural environments with great diversity of habitats and species, causing ecological losses that can lead to large economic and ecosystem losses.
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Parâmetros populacionais de peixes oportunistas da planície de inundação do alto rio Paraná : influências do El Niño Southern Oscillation - ENSO.The occurrences of El Niño - Southern Oscillation – ENSO climate events promote alterations in the global hydrological cycle, so that the precipitation pattern results in periods of extreme drought and floods in certain continental regions. The irregularity of rainfall inconstantly changes the hydrometric level of aquatic bodies, the flood pulse and the river discharge, which in turn alter the limnological variables, the primary productivity and the availability of resources and habitat for the aquatic organisms, possibly affecting their growth and reproduction patterns. Therefore, the population parameters (such as sex ratio, size at first sexual maturity, weight-length ratio and somatic growth) of the short-lived icthyofauna (CVC) in the upper Paraná River floodplain (PIARP) were evaluated and compared in different climate periods (El Niño, La Niña and Neutral) through statistical modeling, under Bayesian perspective. The population parameters were estimated for the Hyphessobrycon eques species, for it was one of the selected species that presented traits of opportunistic strategy, being so characterized as a short life cycle species. The results found partially corroborated with the predictions, that the highest sex ratio found was for the La Niña period (2.7 females for one male), followed by Neutral (2.3) and El Niño (1.3) periods. For the first maturity sizes (L50), estimated for both sexes, they were smaller in the La Niña period (23.87mm for females and 23.35mm for males), followed by the El Niño period (25.89 mm for females and 28.75mm for males) and Neutral period (25.97mm females/ 29.92mm males). The weight-length ratio showed that the male body shape (α) had a slightly higher body biomass (α) average than females in the Neutral and La Niña periods. However, in the El Niño period, the opposite of the other periods was observed. The estimated parameters for the female body shape (α) were higher in Neutral, followed, respectively, by the El Niño and La Niña period, though, for males, the body shape (α) was higher in Neutral, followed by the La Niña and El Niño period. The estimated median lengths for the ages are moderately longer in males than females. Furthermore, the estimated median lengths are relatively longer in extreme periods (La Niña and El Niño) for the initial ages (3 and 6 months) when compared to the Neutral period, both for males or females. For females, the estimated median lengths are comparably longer in the El Niño period than in the La Niña period, while the opposite is observed for males. For that reason, the reproductive tactics of H. eques presented in the La Niña period can be a population level’s response, used for the optimization of the reproductive success and for the maintenance of the species in the environment.
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Alterações na assembleia de peixes antes e após a construção de barragens com trecho de vazão reduzida no rio das Antas, Rio Grande do Sul, Brasil.The demand for electricity around the world has led several countries to construct and to plan more damming in rivers. Nowadays, even small and medium sized rivers are considered for the construction of dams, forming small to medium sized reservoirs, including a reduced flow stretch, once turbines are usually located downriver far from the dam. The purpose of this study was to investigate the effects of small to medium sized reservoirs on fish assemblages, using a Before-After Control-Impact (BACI) design, which includes sampling before and after dammings. Reservoirs were in the cascade of the Antas River (Castro Alves, Monte Claro and 14 de Julho dams and associated reservoirs). Specifically, alterations in the selected attributes (abundance, species richness, Shannon diversity index and evenness) and in the structure of fish assemblages were evaluated. Samples were conducted before and after reservoir filling, in three sampling stations of each reservoir, one located downstream (along the reduced flow stretch), another in the reservoir (lentic area) and the other above the reservoir (lotic stretch). For the collected data, in the three reservoirs, there were variation in abundance, species richness and Shannon diversity Index, always with greater values after the formation of the reservoirs. There were also variations for the sampling sites, with greater values of abundance and species richness downstream the dams. Variations in the structure of fish assemblages, due to the formation of the reservoirs, were also relevant. These variations were more intense in the station located below the dams, followed by the one located inside the reservoir and the one located upstream. The alterations appeared to be lessened because the hydrologic regime of the Antas River works as waves, in which, several times, the wave may pass over the dam, increasing water level downstream. The increases in species richness in the sites sampled seem to be a result of distinct processes. In the reduced flow stretch downstream dams, the increase may be attributed to the accumulation of fish due the obstacle represented by the dam. For the stations inside the reservoirs, the increases are due to samplings in the littoral zone during the trophic upsurge period; fish are known to inhabit the littoral, especially small characids. Finally, for the stations located upstream may be a result of the intense fish movements in this stretch.
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Resposta à inundação de plantas jovens de Albizia niopoides (Spruce ex Benth.) Burkart.Floodplains provide a unique environment, periodic floods cause low rates of diffusion and solubility of oxygen in the soil and represent the main restriction to plant community development. Among the strategies presented by plants that allow them to survive these flooding events are morphophysiological and anatomical adjustments, reducing the damage caused by oxygen deficiency. This study was conducted with the objective of experimentally observing the adaptive strategies of survival to the flooding, thus, young plants of Albizia niopoides (Spruce ex Benth.) Burkart were submitted to water saturation conditions. The following treatments were submitted to the plants: flooded (only the soil submerged in water), submersion (plants totally under the water) and the control group (maintained at field capacity). For morphological evaluation, we collected data from shoot height, root length, biomass (leaves, stem and root). For the anatomical analysis of the root, we measured the diameter of the vascular cylinder of the root and the total diameter of the root, in addition to data about chlorophyll a and b, carotenoids and total chlorophyll. Analyzes were performed 15, 30 and 60 days after the start of the treatments. Results were statistically compared by mean tests (ANOVA, Kruskal-wallis and t-test). In general, the control group presented higher growth averages in the parameters: shoot height, root length, biomass of leaves and root, diameter of the central cylinder of the root and total diameter of the root, compared to the other treatments, in all studied periods. The values of chlorophyll a, b and total and carotenoids showed little variation at 15 days after the beginning of treatments and only at 30 days the control and flooded groups obtained higher values, compared to the totally submerged, indicating changes in the metabolism of plants kept in submersion. Anatomical analysis showed greater development in the control group, with roots in advanced secondary tissue growth and reduced total root diameter in treatments when it was in hypoxia. We observed The presence of lenticels and adventitious roots in the flooded plants. At 60 days after the start of treatments, subjects in the submerged treatment were dead. Flooding represented a negative effect on the growth of individuals as well as substrate flooding. The death of plants under submersion treatment indicates that Albizia niopoides does not tolerate long periods of total submersion, while the morphoanatomical characteristics developed suggest that the plant is considered tolerant to the stress caused by the flooding of the substrate.
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Diversidade taxonômica, funcional e filogenética de protistas ciliados em uma planície de inundação Neotropical: determinantes dos padrões espaciais e temporais da diversidade β e sincronia de comunidade.Patterns of species richness are driven by biotic and abiotic factors and the way in which they operate at spatial and temporal scales. In continental aquatic environments, communities may differ in important aspects such as taxonomic, functional and phylogenetic structure, and the detection of biodiversity may vary between these different facets. For the development of this study, to test important ecological theories, we used the spatial and temporal database of ciliate protists from the upper Paraná River floodplain, from a long-term ecological program - PELD. The spatial and temporal β diversity was verified in three facets of biodiversity (taxonomic, functional and phylogenetic) of the ciliate community, and the contribution of different environmental predictors, using data on composition (presence/absence) and structure (abundance) of the community. It was found that different facets of diversity are influenced by different environmental predictors, but with more evident results for the functional and phylogenetic facets, especially when using data on the structure of the ciliate community. The synchrony between ciliate species in time and space was also evaluated, and the relation of this synchrony with the facets of diversity. Significant relationships were observed between ciliate synchrony and phylogenetic distance, but not for community functional distance. It is concluded that systematic and more precise advances in the community are needed to further improve knowledge about phylogenetic proximities of species and ecosystem functions performed by ciliate protists in limnic environments. Therefore, studies with functional and phylogenetic characteristics of ciliate species are recommended, in future research with application in other ecological theories, with significant contributions in the field of ecology, taxonomy and conservation of this community.
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Priorização espacial para conservação e restauração da interação entre peixes frugívoros e floresta na bacia Paraná-Paraguai.Interactions between frugivorous fish and forests contribute to seed dispersal and the structuring of plant communities in riverine habitat and floodplain forests. However, fish-forest interactions that contribute to maintaining biodiversity are threatened by climate and landscape changes. The objective was to identify areas suitable for the conservation and restoration of fish-forest interaction and related ecosystem services in the Parana-Paraguay River basin, integrating climatically suitable areas for Myloplus tiete and Piaractus mesopotamicus, two species of frugivorous habit, native to the basin, and at risk of becoming extinct. The predictions show a reduction in climate-environmental suitability for the two species at different times (present, 2050, and 2080) and different carbon emission scenarios and low availability of vegetation cover. By multiplying the values of climate suitability with the availability of vegetation, generated the Environmental Optimum Index, which allowed us to identify areas for conservation and restoration. The models demonstrated priority areas for conservation concentrated in the southern portion of the Pantanal and the headwater regions of the upper Parana River basin. At the same time, classified the restoration areas concentrated in the mouth region between the Tietê and Paranapanema rivers. It reinforces the essential that decision-makers prioritize the investment of limited resources for the conservation and restoration of riparian landscapes and develop efficient policies and practices to integrate biodiversity conservation, ecosystem services, and social well-being.
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Macrófitas aquáticas na Região Neotropical: riqueza e qualificação das espécies.Aquatic macrophytes are macroscopic photosynthetic organisms that encompass several taxonomic groups of plants, with broad limnological characteristics that colonize from marshes to submerged areas, playing a fundamental role in structuring wetlands and affecting aquatic biodiversity. The Neotropical Region, covering from the south of Mexico to the south of Argentina, is characterized for being one of the most biodiverse regions in the world, with a unique biota, many endemic species and a great diversity of environments. As one of the wetlands with the greatest potential in this ecozone and the world, the Paraná-Paraguay basins stand out. The objectives of this thesis were to quantify and qualify the species of aquatic macrophytes that occur in the Neotropical Region and in the Paraná-Paraguay basins, carry out an analysis of hotspots for the Paraná-Paraguay basins and provide current information and indicators of areas of high richness of aquatic macrophytes. A conservation efficiency analysis is also available that correlates areas considered hotspots and the protected areas present in these basins. Data from systematic searches in important bibliographic bases were used to compose the lists and geographic coordinates. A total of 1616 spp. for the Neotropics and 979 species for the Paraná-Paraguay basins. The families with the highest number of species were Cyperaceae Juss. and Poaceae Barnhart in both regions studied. Species richness for the Paraná-Paraguay basins was recorded using occurrence points, with 5 locations with values from 71 to 139 species and 50 locations from 1 to 11 species, with the Lower Paraná River having the lowest number of occurrences and the Lower Paraguay River the largest amount. Sixteen sub-basins considered as hotspots were registered, and these areas coincided with the areas of greatest richness. Approximately 6% of the total ecological hotspot areas are being conserved within protected areas. In conclusion, the results obtained in both surveys reaffirm the high number of species present in these wetlands, highlighting the need for further systematic and taxonomic studies of aquatic macrophytes, seeking to precisely detail these megadiverse regions.
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Efeito temporal na parasitofauna do bagre invasor Trachelyopterus galeatus (Linnaeus, 1766) de uma planície Neotropical.Aquatic environments have been anthropically influenced over the years, mainly with the construction of dams and hydroelectric plants. However, few studies evaluate how the parasitic fauna can be influenced in the long term by these environmental changes. Possible changes in the composition of endoparasites of the invasive fish Trachelyopterus galeatus in the upper Paraná River floodplain were investigated over a 27-year study period. 79 fish were analyzed in period 1 (1993) and 31 in period 2 (2019/2020). In the first period, the fish showed higher values in the variables weight (g) and standard length (cm), when compared to period 2. A total of five species of endoparasites were found, three per period. Although the richness was the same, the composition of endoparasites differed between the periods, as only one species of digenetic (Microrchis oligovitellum) parasitized the host in both periods of study. It was found that both the development of the fish and its endoparasites were affected over time. It is noteworthy that the beginning of operation of the Porto Primavera dam, located upstream of the plain, occurred between the two sampling periods (1999), and caused several environmental changes, possibly being the main responsible for these changes in the parasitofauna. Most endoparasites require intermediate hosts to complete their life cycles. Therefore, a modified environment may lose diversity and ecological interactions, as it affects the populations they use during the transmission process between hosts. This may explain the difference found in the infracommunities of T. galeatus parasites, emphasizing, through the results obtained, the importance of including these organisms in studies that evaluate environmental impacts caused by anthropic actions
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Aquatic macrophytes as drivers of multiple aspects of fish community: trophic, functional and taxonomic fish responses in tropical and temperate freshwater ecosystems.Macrophytes are widely recognized for increasing habitat complexity and driving a relevant role in structuring communities in aquatic ecosystems. We investigated how the density, coverage and diversity of macrophytes can influence multiple aspects of fish community, including functional alpha and beta diversity, foraging efficiency, trophic niche breadth and overlap, total abundance and biomass of fish, as well as of certain species and sizes of fish. We used 30 macrophyte stands sampled in the littoral zone of a tropical river, as well as a dataset of 88 shallow temperate lakes. In the latter case, two spatial scales were considered (lake and points within a lake), since there is usually a negative relationship between fish and macrophyte coverage, and this relationship may be more evident at the point scale, while the effect is attenuated at the lake scale. The results showed that macrophytes can select functional characteristics of fish communities and influence their alpha and beta functional diversity. The highest values of functional alpha diversity occurred in intermediate macrophyte density and high macrophyte diversity. The variation in macrophyte density was strongly responsible for variations in functional beta diversity. Fish showed general trophic responses to the variation in macrophyte attributes, but these responses also depended on fish feeding habits, with herbivores niche breadth responding in the opposite way to omnivores. The increase in macrophyte density led to an increase in fish consumption of higher plants and foraging efficiency, and reduced trophic niche breadth. Fish niche overlap was higher at intermediate levels of macrophyte density. Fish responses depended on fish species identity, lake productivity and water depth. The deeper and more eutrophic the lakes, the more fish tended to occupy macrophyte-covered points within a lake. The results emphasize how aquatic plants can affect the fish community by influencing swimming, food availability and interactions between species, and that the relationship between fish and macrophytes can vary according to the scale of the study and the fish characteristics. The application of the results obtained here has great potential to help in projects of management and conservation of biodiversity, and in the choice of the best configurations of macrophyte stands for the maintenance of ichthyofauna.
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Padrões de diversidade beta de macroinvertebrados bentônicos frente ao gradiente de recuperação ambiental em riachos temperados acidificados.The industrial advance of Europe between the 19th and 20th centuries resulted in major environmental impacts. Among these impacts, the deposition of acid compounds through acid rain stands out, and this phenomenon led to the acidification of water bodies. However, from the 1980s on, with the application of stricter environmental regulations, a gradual recovery of abiotic parameters began, including pH values, which began to return to less acidic ranges. Thus, we investigated the responses of the benthic community to the gradual recovery of abiotic variables after years of intense acidification, analyzing changes in community structure and, specifically, variations in beta diversity. The study was developed with data from streams in Wales, collected and provided by two research projects that monitor the region's water bodies. The streams were classified according to abiotic characteristics and the surrounding vegetation (Acid Forest, Acid Moorland and Circumneutral Moorland). In the first approach, the community of 69 streams was analyzed, testing whether (i) the composition of macroinvertebrate communities differed among the types of environments and years analyzed; and whether (ii) in early years beta diversity among streams was lower than in more recent years, as well as in streams of a more acidic category. Samples were collected in 1984, 1995, and 2012, with the earliest year under the greatest influence of acidification. A segregation in macroinvertebrate composition was observed between 1984 and the other years, and this difference in community composition between the years suggests that environmental recovery with rising pH values, allowed the entry and establishment of new macroinvertebrate species in the streams. The lowest beta diversity value was also observed in 1984, indicating biotic homogenization in this period and an increase in community dissimilarity over time. In the second approach, we investigated the hypothesis that a gradual increase in temporal beta diversity (TBI) values occurs over time. This was done by sampling eight streams in Wales over the period 1985 to 2018, and comparing beta diversity between the reference year 1985 with all other years. There was an increase in TBI values over the years for all environments, showing evidence of biological recovery concomitant with restoration of abiotic values. The results contributed to the understanding that the biotic community also responds to environmental recovery, and there are different ways to evaluate this process, such as beta diversity. The importance of long-term research is emphasized so that such changes can be monitored.
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Guiding biological control of alligator weed by Agasicles hygrophila (Coleoptera: Chrysomelidae) at macroscale: where are the potential global areas suitable to apply it and how it can change in climate change scenarios.Invasive species can have many negative impacts on the biodiversity, ecosystem services, human health and the economy, and therefore need to be managed. An amphibious weed of global importance, Alternanthera philoxeroides, and the macroecological patterns of its biological control were evaluated using one of its main specialist herbivores, Agasicles hygrophila. This was considered the first successful case of biological control of an aquatic plant, although it is not equally effective on a global scale. Due to their different environmental tolerances and the greater phenotypic plasticity of the plant, the distribution of both species do not always overlap in the globe, creating geographic variability in the efficiency of biocontrol. The first approach was to analyze the current global potential distribution of A. philoxeroides and A. hygrophila to seek the areas of overlaps and gaps between them. The overlapping areas would be the most relevant for using A. hygrophila as alligator weed biological control in the globe. However, in response of climate change, it seems that the alligator weed is worryingly spreading across the globe, which can worsen in future scenarios and alter its distribution in the next decades. The second approach evaluated the effects of climate change on the global distribution of A. philoxeroides and A. hygrophila. New distribution areas for both species in future global warming scenarios and new overlapping and non-overlapping areas across the globe were identified. Species Distribution Models (SDMs) were applied in both chapters to predict the potential distribution of the two species in present and future scenarios considering different environmental predictors in each one. Currently, the southeast coast of the USA, southeast China and New South Wales, Australia are the most favorable areas in the world to apply alligator weed biocontrol, while the west coast and mid-latitudes in the east of the USA and the eastern Australia are not favorable. The results were corroborated by reports in the literature that demonstrated successful control in overlapping areas and failures in non-overlapping areas of the models’ distributions. However, while general geographic patterns will hold in future scenarios, it is predicted a major northward expansion of the alligator weed, but not of the insect, especially in the USA, Canada, Europe, China, South Korea and Japan, which will create a new zone of low or no control efficiency at higher latitudes. These macroecological patterns will help direct efforts to apply the biological control for the alligator weed not only today, but also in future climate change scenarios.
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Co-occurrence patterns in invaded communities: what drives the spatial distribution of native and non-native species?Invaded communities were evaluated under two contexts: 1) how native communities respond to massive introduction events and 2) how invaded communities change through time. A common topic was defined to represent the modifications in communities after invasion, the co-occurrence between species. The objective of this thesis was to answer three questions: 1) whether the impact caused by non-native species is determined by the level of similarity between native and non-native species; 2) whether the impact would have the same pattern through time; and 3) whether there is any attribute of the non-native species population that determines the level of the impact. The data set from the project Pesquisas Ecológicas de Longa Duração (PELD) performed at the Upper Paraná River floodplain (Sítio PELD/PIAP) was used to answer these questions.First, it was evaluated the non-native species effects on the co-occurrence between species after the invasion of more than 30 non-native fish species at once. It was tested if the functional dissimilarity between native and non-native species drives the co-occurrence patterns between them. After, it was estimated the co-occurrence in a time series of 30 years. The non-native species evaluated were introduced by several introduction vectors. It was tested if the non-native species abundance and time since introduction drive the co-occurrence between native and non-native species. The abundance was used as the attribute of non-native species population to test if the effect of abundance is mediated by the phylogenetic distance between species. The results found showed that the co-occurrence between native and non-native species is affected by functional and phylogenetic distance. Therefore, integrating functional and phylogenetic diversity to assess the spatial distribution of organisms has potential to improve the understanding of co-occurrence patterns between native and non-native species. The results also showed that co-occurrence patterns may be more sensitive to the temporal variability in non-native population attributes (i.e. abundance) than time since introduction. It was showed that evaluating patterns of several non-native species may provide a broader understating of the entire community after invasions.
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Trends and challenges in alternative states in freshwater ecosystems: emphasizing the role of invasive species in state shifts.Despite growing interest in the effects of non-native invasive species in changing alternative trophic states in shallow lakes, little is known when it comes to tropical regions. We carried out a systematic review to identify which terms, species, definitions and objectives were most addressed in these studies, as well as to identify possible global patterns and trends regarding the growth of these research over the years and the hot spots of publications. Our results showed that although there was a non-linear growth in the number of studies published in the last three decades regarding state shifts in freshwater environments, only a small number of them addresses the influence that non-native invasive species have in triggering trophic states changes in aquatic environments and even less in shallow lakes. In our discussion, we explore the possible reasons and consequences that these patterns bring to this area of ecology, as well as expand the results and make the work available so that it can be used as recomendation for future projects related to the topic.
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Respostas de espécies invasoras de Poaceae ao estresse hídrico, a competição com nativas filogeneticamente próximas e a mudança climática global.Global climate change has as its main result an increase in the frequency and severity of extreme events, such as longer periods of drought, and more hot days throughout the year, which makes drought events even more severe. Certain plant species have a high invasive potential, which is due to their tolerance to adverse conditions and the recovery of their individuals after some disturbance, which increases the possibility of colonization and establishment in new environments, interfering with native communities. The effect of interspecific competition between the invasive plant Urochloa mutica and the native species Panicum dichotomiflorum was experimentally analyzed on its establishment, resistance and resilience, simulating conditions of extreme water events and the distribution of Panicum dichotomiflorum and Urochloa mutica, particularly in protected areas environmental. The results obtained showed that the native species grew less with the water changes, mainly due to the lack of water, and the invasive species did not show strong growth alterations with the disturbances used. Furthermore, the species were shown to alter the growth variables in competition, impacting the native species more. On the other hand, the species in terms of temporal stability did not change growth and both may have advantages in impacted environments. Regarding the distribution of species, the results showed that the dispersion of the invasive exotic plant will be greater in areas that already have its presence, and also that this species may invade new places, such as Germany and Austria. In a future scenario of global climate change in 2070, this invasive species could occur in protected areas. Regarding the national territory, U. mutica will lose part of its distribution in Brazil, mainly in the north and northeast regions, including areas of protection and conservation. For P. dichotomiflorum, it is possible that it will lose a large part of its natural habitat in the two future scenarios, but it will increase its occurrence in other places, being able to become a potential invasive. Therefore, the results achieved indicate that both species have important characteristics in coping with climate change and show that the native species has an invasive behavior, with information of enormous value to environmental managers, especially in the management work of the two species of Poaceae, which have invasive potential for preserved areas, and in research that evidence areas susceptible to invasion.
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Efeito de barramento e de eventos hidrológicos extremos sobre os padrões de diversidade beta funcional do fitoplâncton de planície de inundação.Dams and predicted future extreme weather events can affect the structure of aquatic communities, both at a local and regional scale. They can influence, for example, the importance of sites and species for regional diversity as they promote local processes of extinction and colonization, as well as processes of biotic homogenization on a regional scale. It was investigated how damming and prolonged flood and drought periods influenced the local contribution to beta diversity (LCBD) based on phytoplankton functional groups (GFR), as well as the contribution of each GFR to beta diversity (SCBD). The relationship between the number of GFR (Functional richness - RF) on the LCBD was also evaluated. For this, it was analyzed data collected in years with extreme drought (2000-2001) and flood (2010-2011) from three sub-basins of the upper Paraná River floodplain were used, which have different damming effects (presence, indirect influence, and absence). Nutrient concentrations and pH influenced the beta diversity in the three sub-basins in the two periods. Extreme drought periods and the presence of a dam were related to higher values of LCBD and RF. High LCBD values were related to low RF values. Environments with the absence and indirect influence of the dam had higher RF values in the flood and higher LCBD values in the drought. GFR H1 (N-fixing cyanobacteria), Lo (large mucilaginous cyanobacteria), and P (filamentous diatoms) presented the greatest contribution to beta diversity. The damming region was related to filamentous cyanobacteria in the drought. The results showed that both damming and climatic periods influenced the contribution of sites to regional diversity. However, they also suggested that the greatest biotic uniqueness observed in the damming region and in the dry period was related to organisms that can affect water diversity and quality, such as cyanobacteria. It appears that these environments have unique environmental and biotic conditions that require greater attention in terms of monitoring to prevent the proliferation of organisms with toxigenic potential. The construction of dams in search of energy security, associated with the predicted scenario of an increase in extreme events, favors biotic uniqueness. Understanding how communities respond to these changes is crucial for the ecology of aquatic environments.
